4 Signs You Have A Food Allergy Other Than Breaking Out In Hives

If you were one of the lucky kids who got through childhood without a food allergy, you probably figure you're in the clear now that you're a grownup. While most food allergies do start in childhood, it's not uncommon for adults to suddenly react to a food they've eaten before without any problems: One study found that at least 15% of people with food allergies develop them for the first time between the ages of 18 and 86.

Meanwhile, the prevalence of of food allergies in adults seems to be on the rise. "We don't really understand the mechanism, but something triggers the immune system to have an abnormal reaction to one or more proteins in a food," says Sujan Patel, MD, assistant professor of infectious disease and immunology and pediatrics at NYU Langone Medical Center. (Learn how simple it is to control your blood sugar with food—no pills needed!—with the easy plan in The Natural Way To Beat Diabetes.)

When the immune system responds this way, symptoms usually strike quickly—often within minutes of eating the offending food (shellfish and tree nuts are the most common triggers in adults), though they sometimes take up to two hours to develop. The most well-known sign of a food allergy is an itchy rash, but according to Patel there's often a constellation of symptoms that can occur throughout the body. Here are others to look out for.

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GI issues

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After you're exposed to a food protein that your immune system mistakenly thinks is harmful, it releases antibodies and other chemicals called histamines to help expel the "invader" from your body. The symptoms you develop depend on where in the body the histamine is released. If it's released in the skin, for example, you may develop hives, flushing, swelling, or a rash. If it's released in the gastrointestinal tract, it can cause symptoms like nausea, diarrhea, abdominal pain, and vomiting. (If you feel bloated, here are 7 ways GI docs beat their own bloat.)

When GI symptoms occur, it can be easy to mistake them for the flu or food poisoning, says Patel. One tip off it's a food allergy: The vomiting or cramps is often also accompanied by non-GI-related symptoms, like a scratchy throat or swelling of the lips. If you suspect you might be experiencing symptoms of a food allergy, it's important to seek medical care. Even if your symptoms are relatively mild, you can't predict whether they'll become more severe or potentially life-threatening during a subsequent episode. Plus, there's some evidence that reactions in adults tend to be more severe.

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Sneezing and congestion

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It might seem like you're coming down with a cold, but sneezing, a runny nose, and nasal congestion that seems to come on after eating a certain food could signal a food allergy. The reason is simple: Histamine is being released in your respiratory tract. Your tongue might also swell, or you might notice a metallic taste in your mouth.

So-called "oral allergy symptom" happens when someone who's allergic to pollen eats a fruit or vegetable that contains similar proteins. This is the most common type of adult food allergy, and the symptoms tend to be confined to the mouth and throat, says Wayne G. Shreffler, MD, PhD, director of the food allergy center at Massachusetts General Hospital. For example, people allergic to birch pollen may develop reactions to a related group of nuts and fruits like almonds, hazelnuts, apples, and pitted fruits. Those who are allergic to ragweed often have trouble eating melons and bananas.

Symptoms of OAS, which are generally mild form, usually appear immediately after eating the raw fruit or vegetable. The good news is that the same food is usually fine to eat when it's cooked because heat breaks down the problematic proteins.

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Anaphylactic shock

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The most severe manifestation of a food allergy, anaphylactic shock is a life-threatening reaction that requires emergency treatment. "Anaphylaxis is a combination of symptoms that involves different body systems, including the respiratory and gastrointestinal tracts, skin, and cardiovascular system," explains Patel. Symptoms includes difficulty breathing, swelling of the upper throat and/or tongue, a very rapid or irregular heartbeat, low blood pressure, or cardiac arrest (when the heart stops beating). If you have any of these, get help right away; you'll likely need an injection of epinephrine (adrenaline). (If you have any of these symptoms, you should get to the ER stat.)

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